opencv/modules/features2d/src/draw.cpp

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#include "precomp.hpp"

const int draw_shift_bits = 4;
const int draw_multiplier = 1 << draw_shift_bits;

namespace cv
{

/*
 * Functions to draw keypoints and matches.
 */
static inline void _drawKeypoint( InputOutputArray img, const KeyPoint& p, const Scalar& color, DrawMatchesFlags flags )
{
    CV_Assert( !img.empty() );
    Point center( cvRound(p.pt.x * draw_multiplier), cvRound(p.pt.y * draw_multiplier) );

    if( !!(flags & DrawMatchesFlags::DRAW_RICH_KEYPOINTS) )
    {
        int radius = cvRound(p.size/2 * draw_multiplier); // KeyPoint::size is a diameter

        // draw the circles around keypoints with the keypoints size
        circle( img, center, radius, color, 1, LINE_AA, draw_shift_bits );

        // draw orientation of the keypoint, if it is applicable
        if( p.angle != -1 )
        {
            float srcAngleRad = p.angle*(float)CV_PI/180.f;
            Point orient( cvRound(cos(srcAngleRad)*radius ),
                          cvRound(sin(srcAngleRad)*radius )
                        );
            line( img, center, center+orient, color, 1, LINE_AA, draw_shift_bits );
        }
#if 0
        else
        {
            // draw center with R=1
            int radius = 1 * draw_multiplier;
            circle( img, center, radius, color, 1, LINE_AA, draw_shift_bits );
        }
#endif
    }
    else
    {
        // draw center with R=3
        int radius = 3 * draw_multiplier;
        circle( img, center, radius, color, 1, LINE_AA, draw_shift_bits );
    }
}

void drawKeypoints( InputArray image, const std::vector<KeyPoint>& keypoints, InputOutputArray outImage,
                    const Scalar& _color, DrawMatchesFlags flags )
{
    CV_INSTRUMENT_REGION();

    if( !(flags & DrawMatchesFlags::DRAW_OVER_OUTIMG) )
    {
        if( image.type() == CV_8UC3 )
        {
            image.copyTo( outImage );
        }
        else if( image.type() == CV_8UC1 )
        {
            cvtColor( image, outImage, COLOR_GRAY2BGR );
        }
        else
        {
            CV_Error( Error::StsBadArg, "Incorrect type of input image.\n" );
        }
    }

    RNG& rng=theRNG();
    bool isRandColor = _color == Scalar::all(-1);

    CV_Assert( !outImage.empty() );
    std::vector<KeyPoint>::const_iterator it = keypoints.begin(),
                                     end = keypoints.end();
    for( ; it != end; ++it )
    {
        Scalar color = isRandColor ? Scalar(rng(256), rng(256), rng(256)) : _color;
        _drawKeypoint( outImage, *it, color, flags );
    }
}

static void _prepareImgAndDrawKeypoints( InputArray img1, const std::vector<KeyPoint>& keypoints1,
                                         InputArray img2, const std::vector<KeyPoint>& keypoints2,
                                         InputOutputArray _outImg, Mat& outImg1, Mat& outImg2,
                                         const Scalar& singlePointColor, DrawMatchesFlags flags )
{
    Mat outImg;
    Size img1size = img1.size(), img2size = img2.size();
    Size size( img1size.width + img2size.width, MAX(img1size.height, img2size.height) );
    if( !!(flags & DrawMatchesFlags::DRAW_OVER_OUTIMG) )
    {
        outImg = _outImg.getMat();
        if( size.width > outImg.cols || size.height > outImg.rows )
            CV_Error( Error::StsBadSize, "outImg has size less than need to draw img1 and img2 together" );
        outImg1 = outImg( Rect(0, 0, img1size.width, img1size.height) );
        outImg2 = outImg( Rect(img1size.width, 0, img2size.width, img2size.height) );
    }
    else
    {
        _outImg.create( size, CV_MAKETYPE(img1.depth(), 3) );
        outImg = _outImg.getMat();
        outImg = Scalar::all(0);
        outImg1 = outImg( Rect(0, 0, img1size.width, img1size.height) );
        outImg2 = outImg( Rect(img1size.width, 0, img2size.width, img2size.height) );

        if( img1.type() == CV_8U )
            cvtColor( img1, outImg1, COLOR_GRAY2BGR );
        else
            img1.copyTo( outImg1 );

        if( img2.type() == CV_8U )
            cvtColor( img2, outImg2, COLOR_GRAY2BGR );
        else
            img2.copyTo( outImg2 );
    }

    // draw keypoints
    if( !(flags & DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS) )
    {
        Mat _outImg1 = outImg( Rect(0, 0, img1size.width, img1size.height) );
        drawKeypoints( _outImg1, keypoints1, _outImg1, singlePointColor, flags | DrawMatchesFlags::DRAW_OVER_OUTIMG );

        Mat _outImg2 = outImg( Rect(img1size.width, 0, img2size.width, img2size.height) );
        drawKeypoints( _outImg2, keypoints2, _outImg2, singlePointColor, flags | DrawMatchesFlags::DRAW_OVER_OUTIMG );
    }
}

static inline void _drawMatch( InputOutputArray outImg, InputOutputArray outImg1, InputOutputArray outImg2 ,
                          const KeyPoint& kp1, const KeyPoint& kp2, const Scalar& matchColor, DrawMatchesFlags flags )
{
    RNG& rng = theRNG();
    bool isRandMatchColor = matchColor == Scalar::all(-1);
    Scalar color = isRandMatchColor ? Scalar( rng(256), rng(256), rng(256) ) : matchColor;

    _drawKeypoint( outImg1, kp1, color, flags );
    _drawKeypoint( outImg2, kp2, color, flags );

    Point2f pt1 = kp1.pt,
            pt2 = kp2.pt,
            dpt2 = Point2f( std::min(pt2.x+outImg1.size().width, float(outImg.size().width-1)), pt2.y );

    line( outImg,
          Point(cvRound(pt1.x*draw_multiplier), cvRound(pt1.y*draw_multiplier)),
          Point(cvRound(dpt2.x*draw_multiplier), cvRound(dpt2.y*draw_multiplier)),
          color, 1, LINE_AA, draw_shift_bits );
}

void drawMatches( InputArray img1, const std::vector<KeyPoint>& keypoints1,
                  InputArray img2, const std::vector<KeyPoint>& keypoints2,
                  const std::vector<DMatch>& matches1to2, InputOutputArray outImg,
                  const Scalar& matchColor, const Scalar& singlePointColor,
                  const std::vector<char>& matchesMask, DrawMatchesFlags flags )
{
    if( !matchesMask.empty() && matchesMask.size() != matches1to2.size() )
        CV_Error( Error::StsBadSize, "matchesMask must have the same size as matches1to2" );

    Mat outImg1, outImg2;
    _prepareImgAndDrawKeypoints( img1, keypoints1, img2, keypoints2,
                                 outImg, outImg1, outImg2, singlePointColor, flags );

    // draw matches
    for( size_t m = 0; m < matches1to2.size(); m++ )
    {
        if( matchesMask.empty() || matchesMask[m] )
        {
            int i1 = matches1to2[m].queryIdx;
            int i2 = matches1to2[m].trainIdx;
            CV_Assert(i1 >= 0 && i1 < static_cast<int>(keypoints1.size()));
            CV_Assert(i2 >= 0 && i2 < static_cast<int>(keypoints2.size()));

            const KeyPoint &kp1 = keypoints1[i1], &kp2 = keypoints2[i2];
            _drawMatch( outImg, outImg1, outImg2, kp1, kp2, matchColor, flags );
        }
    }
}

void drawMatches( InputArray img1, const std::vector<KeyPoint>& keypoints1,
                  InputArray img2, const std::vector<KeyPoint>& keypoints2,
                  const std::vector<std::vector<DMatch> >& matches1to2, InputOutputArray outImg,
                  const Scalar& matchColor, const Scalar& singlePointColor,
                  const std::vector<std::vector<char> >& matchesMask, DrawMatchesFlags flags )
{
    if( !matchesMask.empty() && matchesMask.size() != matches1to2.size() )
        CV_Error( Error::StsBadSize, "matchesMask must have the same size as matches1to2" );

    Mat outImg1, outImg2;
    _prepareImgAndDrawKeypoints( img1, keypoints1, img2, keypoints2,
                                 outImg, outImg1, outImg2, singlePointColor, flags );

    // draw matches
    for( size_t i = 0; i < matches1to2.size(); i++ )
    {
        for( size_t j = 0; j < matches1to2[i].size(); j++ )
        {
            int i1 = matches1to2[i][j].queryIdx;
            int i2 = matches1to2[i][j].trainIdx;
            if( matchesMask.empty() || matchesMask[i][j] )
            {
                const KeyPoint &kp1 = keypoints1[i1], &kp2 = keypoints2[i2];
                _drawMatch( outImg, outImg1, outImg2, kp1, kp2, matchColor, flags );
            }
        }
    }
}
}